Rocky Shores

Photo credit: Peter Taylor.

Rocky shores are home to some of the most biologically diverse and productive communities throughout the world. These ecosystems lie at the interface between the land and the sea, exposing organisms here to alternating terrestrial and marine habitats in rhythm with the tidal cycle.

When the tide is in, plants and animals are bathed by seawater that exposes them to predators, moderates temperatures, delivers food, transports propagules, and imposes large hydrodynamic forces. When the tide is out, the same rocky-shore species are subjected to terrestrial predators, desiccation, temperature extremes, intense solar radiation, and occasional dousing by freshwater. On rocky shores, invertebrates and algae live in horizontal zones between the high and low tide marks. The zones reflect the varying abilities of species to tolerate the environmental conditions, predation, and competitive pressures at different heights. Intertidal organisms must survive in both terrestrial and marine worlds, transitioning as often as twice each day with the tides. Despite this apparent adversity, rocky shores are home to a striking diversity of species.

A Valuable Baseline

Rocky shores have become a favorite testing ground and experimental ‘laboratory’ for ecologists worldwide. Thanks to their steep environmental gradient, their two-dimensional structure, and the rapid turnover of their abundant sessile or slow-moving organisms, wave swept rocky shores make it practical for ecologists to conduct experiments that would be difficult or impossible elsewhere. Much of what we know about the ecological importance of processes such as competition, recruitment, predation, and patch dynamics has been tested on rocky shores. Although rocky shores are a comparatively minor habitat on Earth in terms of area, they have played a disproportionately large role in our understanding of ecological systems. As we move into an era of accelerated global climate change and expanded human domination of ecosystems, the extensive past work in the intertidal zone may serve as a valuable baseline against which to measure the effects of environmental shifts.

Photo credit: Gil Rilov

PISCO’s research focus on rocky shore habitats reflects their ecological and scientific importance along the coastal region of the California current ecosystem. PISCO continues to monitor biologically important variables such as invertebrate recruitment, community structure and biodiversity as well as physically relevant parameters such as organism body temperatures, submersion times and wave forces in an effort to characterize the importance of processes driving the structure and function of these ecosystems and how they may be affected by changing climate conditions. Additionally rocky shores are one of the key habitat types designated for protection within California’s newly evolving system of marine protected areas, and PISCO’s work in these systems has been and will continue to be critical to understanding the importance of human impacts on these ecosystems.